<template>
  <table
    cellspacing="0"
    cellpadding="0"
    class="el-date-table"
    @click="handleClick"
    @mousemove="handleMouseMove"
    :class="{ 'is-week-mode': selectionMode === 'week' }">
    <tbody>
    <tr>
      <th v-if="showWeekNumber">{{ t('el.datepicker.week') }}</th>
      <th v-for="(week, key) in WEEKS" :key="key">{{ t('el.datepicker.weeks.' + week) }}</th>
    </tr>
    <tr
      class="el-date-table__row"
      v-for="(row, key) in rows"
      :class="{ current: isWeekActive(row[1]) }"
      :key="key">
      <td
        v-for="(cell, key) in row"
        :class="getCellClasses(cell)"
        :key="key">
        <div :class="{ 'is-weekend': [6,7].includes(cell.lunar.nWeek), 'is-work':cell.lunar.isWork, 'is-holiday':cell.lunar.isHoliday }">
          <span>
            {{ cell.text }}
          </span>
          <section style="position: relative; top: 14px;">
            {{cell.lunar.lunarFestival?cell.lunar.lunarFestival:(cell.lunar.festival ? cell.lunar.festival: (cell.lunar.IDayCn == '初一'? cell.lunar.IMonthCn:cell.lunar.IDayCn )) }}
          </section>
        </div>
      </td>
    </tr>
    </tbody>
  </table>
</template>

<script>
import { getFirstDayOfMonth, getDayCountOfMonth, getWeekNumber, getStartDateOfMonth, prevDate, nextDate, isDate, clearTime as _clearTime } from 'element-ui/src/utils/date-util'
import Locale from 'element-ui/src/mixins/locale'
import { arrayFindIndex, arrayFind, coerceTruthyValueToArray } from 'element-ui/src/utils/util'
import calendar from '@/utils/date'

const WEEKS = ['sun', 'mon', 'tue', 'wed', 'thu', 'fri', 'sat']
const getDateTimestamp = function (time) {
  if (typeof time === 'number' || typeof time === 'string') {
    return _clearTime(new Date(time)).getTime()
  } else if (time instanceof Date) {
    return _clearTime(time).getTime()
  } else {
    return NaN
  }
}

// remove the first element that satisfies `pred` from arr
// return a new array if modification occurs
// return the original array otherwise
const removeFromArray = function (arr, pred) {
  const idx = typeof pred === 'function' ? arrayFindIndex(arr, pred) : arr.indexOf(pred)
  return idx >= 0 ? [...arr.slice(0, idx), ...arr.slice(idx + 1)] : arr
}

export default {
  mixins: [Locale],

  props: {
    firstDayOfWeek: {
      default: 7,
      type: Number,
      validator: val => val >= 1 && val <= 7
    },

    value: {},

    defaultValue: {
      validator (val) {
        // either: null, valid Date object, Array of valid Date objects
        return val === null || isDate(val) || (Array.isArray(val) && val.every(isDate))
      }
    },

    date: {},

    selectionMode: {
      default: 'day'
    },

    showWeekNumber: {
      type: Boolean,
      default: false
    },

    disabledDate: {},

    cellClassName: {},

    minDate: {},

    maxDate: {},

    rangeState: {
      default () {
        return {
          endDate: null,
          selecting: false
        }
      }
    }
  },

  computed: {
    offsetDay () {
      const week = this.firstDayOfWeek
      // 周日为界限，左右偏移的天数，3217654 例如周一就是 -1，目的是调整前两行日期的位置
      return week > 3 ? 7 - week : -week
    },

    WEEKS () {
      const week = this.firstDayOfWeek
      return WEEKS.concat(WEEKS).slice(week, week + 7)
    },

    year () {
      return this.date.getFullYear()
    },

    month () {
      return this.date.getMonth()
    },

    startDate () {
      return getStartDateOfMonth(this.year, this.month)
    },

    rows () {
      // TODO: refactory rows / getCellClasses
      const date = new Date(this.year, this.month, 1)
      let day = getFirstDayOfMonth(date) // day of first day
      const dateCountOfMonth = getDayCountOfMonth(date.getFullYear(), date.getMonth())
      const dateCountOfLastMonth = getDayCountOfMonth(date.getFullYear(), (date.getMonth() === 0 ? 11 : date.getMonth() - 1))

      day = (day === 0 ? 7 : day)

      const offset = this.offsetDay
      const rows = this.tableRows
      let count = 1

      const startDate = this.startDate
      const disabledDate = this.disabledDate
      const cellClassName = this.cellClassName
      const selectedDate = this.selectionMode === 'dates' ? coerceTruthyValueToArray(this.value) : []
      const now = getDateTimestamp(new Date())

      for (let i = 0; i < 6; i++) {
        const row = rows[i]

        if (this.showWeekNumber) {
          if (!row[0]) {
            row[0] = { type: 'week', text: getWeekNumber(nextDate(startDate, i * 7 + 1)), lunar: calendar.solar2lunar(this.year, this.month, nextDate(startDate, i * 7 + 1)) }
          }
        }

        for (let j = 0; j < 7; j++) {
          let cell = row[this.showWeekNumber ? j + 1 : j]
          if (!cell) {
            cell = { row: i, column: j, type: 'normal', inRange: false, start: false, end: false }
          }

          cell.type = 'normal'

          const index = i * 7 + j
          const time = nextDate(startDate, index - offset).getTime()
          cell.inRange = time >= getDateTimestamp(this.minDate) && time <= getDateTimestamp(this.maxDate)
          cell.start = this.minDate && time === getDateTimestamp(this.minDate)
          cell.end = this.maxDate && time === getDateTimestamp(this.maxDate)
          const isToday = time === now

          if (isToday) {
            cell.type = 'today'
          }

          if (i >= 0 && i <= 1) {
            const numberOfDaysFromPreviousMonth = day + offset < 0 ? 7 + day + offset : day + offset

            if (j + i * 7 >= numberOfDaysFromPreviousMonth) {
              cell.text = count++
              console.log(calendar.solar2lunar(this.year, this.month + 1, cell.text))
              cell.lunar = calendar.solar2lunar(this.year, this.month + 1, cell.text)
            } else {
              cell.text = dateCountOfLastMonth - (numberOfDaysFromPreviousMonth - j % 7) + 1 + i * 7
              cell.type = 'prev-month'
              cell.lunar = calendar.solar2lunar(this.year, this.month, cell.text)
            }
          } else {
            if (count <= dateCountOfMonth) {
              cell.text = count++
              cell.lunar = calendar.solar2lunar(this.year, this.month + 1, cell.text)
            } else {
              cell.text = count++ - dateCountOfMonth
              cell.type = 'next-month'
              cell.lunar = calendar.solar2lunar(this.year, this.month + 2, cell.text)
            }
          }

          const cellDate = new Date(time)
          cell.disabled = typeof disabledDate === 'function' && disabledDate(cellDate)
          cell.selected = arrayFind(selectedDate, date => date.getTime() === cellDate.getTime())
          cell.customClass = typeof cellClassName === 'function' && cellClassName(cellDate)
          this.$set(row, this.showWeekNumber ? j + 1 : j, cell)
        }

        if (this.selectionMode === 'week') {
          const start = this.showWeekNumber ? 1 : 0
          const end = this.showWeekNumber ? 7 : 6
          const isWeekActive = this.isWeekActive(row[start + 1])

          row[start].inRange = isWeekActive
          row[start].start = isWeekActive
          row[end].inRange = isWeekActive
          row[end].end = isWeekActive
        }
      }

      return rows
    }
  },

  watch: {
    'rangeState.endDate' (newVal) {
      this.markRange(this.minDate, newVal)
    },

    minDate (newVal, oldVal) {
      if (getDateTimestamp(newVal) !== getDateTimestamp(oldVal)) {
        this.markRange(this.minDate, this.maxDate)
      }
    },

    maxDate (newVal, oldVal) {
      if (getDateTimestamp(newVal) !== getDateTimestamp(oldVal)) {
        this.markRange(this.minDate, this.maxDate)
      }
    }
  },

  data () {
    return {
      tableRows: [[], [], [], [], [], []],
      lastRow: null,
      lastColumn: null
    }
  },

  methods: {
    cellMatchesDate (cell, date) {
      const value = new Date(date)
      return this.year === value.getFullYear() &&
          this.month === value.getMonth() &&
          Number(cell.text) === value.getDate()
    },

    getCellClasses (cell) {
      const selectionMode = this.selectionMode
      const defaultValue = this.defaultValue ? Array.isArray(this.defaultValue) ? this.defaultValue : [this.defaultValue] : []

      const classes = []
      if ((cell.type === 'normal' || cell.type === 'today') && !cell.disabled) {
        classes.push('available')
        if (cell.type === 'today') {
          classes.push('today')
        }
      } else {
        classes.push(cell.type)
      }

      if (cell.type === 'normal' && defaultValue.some(date => this.cellMatchesDate(cell, date))) {
        classes.push('default')
      }

      if (selectionMode === 'day' && (cell.type === 'normal' || cell.type === 'today') && this.cellMatchesDate(cell, this.value)) {
        classes.push('current')
      }

      if (cell.inRange && ((cell.type === 'normal' || cell.type === 'today') || this.selectionMode === 'week')) {
        classes.push('in-range')

        if (cell.start) {
          classes.push('start-date')
        }

        if (cell.end) {
          classes.push('end-date')
        }
      }

      if (cell.disabled) {
        classes.push('disabled')
      }

      if (cell.selected) {
        classes.push('selected')
      }

      if (cell.customClass) {
        classes.push(cell.customClass)
      }

      return classes.join(' ')
    },

    getDateOfCell (row, column) {
      const offsetFromStart = row * 7 + (column - (this.showWeekNumber ? 1 : 0)) - this.offsetDay
      return nextDate(this.startDate, offsetFromStart)
    },

    isWeekActive (cell) {
      if (this.selectionMode !== 'week') return false
      const newDate = new Date(this.year, this.month, 1)
      const year = newDate.getFullYear()
      const month = newDate.getMonth()

      if (cell.type === 'prev-month') {
        newDate.setMonth(month === 0 ? 11 : month - 1)
        newDate.setFullYear(month === 0 ? year - 1 : year)
      }

      if (cell.type === 'next-month') {
        newDate.setMonth(month === 11 ? 0 : month + 1)
        newDate.setFullYear(month === 11 ? year + 1 : year)
      }

      newDate.setDate(parseInt(cell.text, 10))

      if (isDate(this.value)) {
        const dayOffset = (this.value.getDay() - this.firstDayOfWeek + 7) % 7 - 1
        const weekDate = prevDate(this.value, dayOffset)
        return weekDate.getTime() === newDate.getTime()
      }
      return false
    },

    markRange (minDate, maxDate) {
      minDate = getDateTimestamp(minDate)
      maxDate = getDateTimestamp(maxDate) || minDate;
      [minDate, maxDate] = [Math.min(minDate, maxDate), Math.max(minDate, maxDate)]

      const startDate = this.startDate
      const rows = this.rows
      for (let i = 0, k = rows.length; i < k; i++) {
        const row = rows[i]
        for (let j = 0, l = row.length; j < l; j++) {
          if (this.showWeekNumber && j === 0) continue

          const cell = row[j]
          const index = i * 7 + j + (this.showWeekNumber ? -1 : 0)
          const time = nextDate(startDate, index - this.offsetDay).getTime()

          cell.inRange = minDate && time >= minDate && time <= maxDate
          cell.start = minDate && time === minDate
          cell.end = maxDate && time === maxDate
        }
      }
    },

    handleMouseMove (event) {
      if (!this.rangeState.selecting) return

      let target = event.target
      if (target.tagName === 'SPAN') {
        target = target.parentNode.parentNode
      }
      if (target.tagName === 'DIV') {
        target = target.parentNode
      }
      if (target.tagName !== 'TD') return

      const row = target.parentNode.rowIndex - 1
      const column = target.cellIndex

      // can not select disabled date
      if (this.rows[row][column].disabled) return

      // only update rangeState when mouse moves to a new cell
      // this avoids frequent Date object creation and improves performance
      if (row !== this.lastRow || column !== this.lastColumn) {
        this.lastRow = row
        this.lastColumn = column
        this.$emit('changerange', {
          minDate: this.minDate,
          maxDate: this.maxDate,
          rangeState: {
            selecting: true,
            endDate: this.getDateOfCell(row, column)
          }
        })
      }
    },

    handleClick (event) {
      let target = event.target
      if (target.tagName === 'SPAN' || target.tagName == 'SECTION') {
        target = target.parentNode.parentNode
      }
      if (target.tagName === 'DIV') {
        target = target.parentNode
      }

      if (target.tagName !== 'TD') return

      const row = target.parentNode.rowIndex - 1
      const column = this.selectionMode === 'week' ? 1 : target.cellIndex
      const cell = this.rows[row][column]

      if (cell.disabled || cell.type === 'week') return

      const newDate = this.getDateOfCell(row, column)

      if (this.selectionMode === 'range') {
        if (!this.rangeState.selecting) {
          this.$emit('pick', { minDate: newDate, maxDate: null })
          this.rangeState.selecting = true
        } else {
          if (newDate >= this.minDate) {
            this.$emit('pick', { minDate: this.minDate, maxDate: newDate })
          } else {
            this.$emit('pick', { minDate: newDate, maxDate: this.minDate })
          }
          this.rangeState.selecting = false
        }
      } else if (this.selectionMode === 'day') {
        this.$emit('pick', newDate)
      } else if (this.selectionMode === 'week') {
        const weekNumber = getWeekNumber(newDate)
        const value = newDate.getFullYear() + 'w' + weekNumber
        this.$emit('pick', {
          year: newDate.getFullYear(),
          week: weekNumber,
          value: value,
          date: newDate
        })
      } else if (this.selectionMode === 'dates') {
        const value = this.value || []
        const newValue = cell.selected
          ? removeFromArray(value, date => date.getTime() === newDate.getTime())
          : [...value, newDate]
        this.$emit('pick', newValue)
      }
    }
  }
}
</script>
<style lang="scss">
$primary: skyblue;
  .el-date-table td{
    height: 45px;
  }
  .el-date-table td span{
    z-index: 9;
  }
  .el-date-table td.start-date section, .el-date-table td.end-date section{
    color: #333;
  }
  .el-date-table td.start-date span, .el-date-table td.end-date span{
    color: #FFFFFF;
  }
  .el-date-table td div{
    height: 45px;
  }
  .available .is-weekend{
    color: red !important;
    &:hover{
      color: $primary !important;
    }
  }
  .available .is-work{
    color: #606266 !important;
    &:hover{
      color: $primary !important;
    }
  }
  .available .is-holiday{
    color: red !important;
    &:hover{
      color: $primary !important;
    }
  }
  .prev-month .is-weekend,
  .next-month .is-weekend,
  .prev-month .is-holiday,
  .next-month .is-holiday{
    color: #ef5f5f !important;
  }
</style>
